It largely depends on the properties of the ingredients of the mixture and their ratio.

There are several types of asphalt concrete, the composition of which differs markedly. In some cases, the composition and quality of the original ingredients are associated with the method of production.

• So, for 1–3 climate zone dense and high-density AB are made of crushed stone, whose frost resistance class is F50. Porous and highly porous - from stone class F 15 and F25.
• For zones 4 and 5, only high-density hot asphalt is made on the basis of crushed stone class F 50

We will talk about the role of sand in the composition of asphalt concrete below.

Sand

It is added to any types of AB, but in some - sandy asphalt concrete, it acts as the only mineral part. are used both natural - from quarries, and obtained by screening during crushing. Material requirements are dictated by GOST 8736.

• So, for dense and high-density sand with a strength class of 800 and 1000 is suitable. For porous ones, it decreases to 400.
• The number of clay particles - less than 0.16 mm in diameter, is also regulated: for dense ones - 0.5%. For porous - 1%.
• increases the ability of AB to swell and reduces frost resistance, so this factor is monitored especially.

mineral powder

This part forms a binder together with bitumen. Also, the powder fills the pores between large stone particles, which reduces internal friction. The grain sizes are extremely small - 0.074 mm. Get them from the system of dust collectors.

In fact, mineral powder is produced from the waste of cement and metallurgical enterprises - this is cement fly-away dust, ash and slag mixtures, waste from the processing of metallurgical slags. The grain composition, the amount of water-soluble compounds, water resistance, etc. are regulated by GOST 16557.

Additional components

To improve the composition or impart some specific properties, various additives are introduced into the initial mixture. They are divided into 2 main groups:

• components designed and manufactured specifically to improve properties - plasticizers, stabilizers, anti-aging agents, etc.;
• waste or secondary raw materials - sulfur, granulated rubber, and so on. The cost of such additives, of course, is much less.

The selection and design of the composition of road and airfield asphalt concrete are discussed below.

The video below will tell about sampling to assess the composition and quality of asphalt concrete:

Design

The composition of the asphalt concrete pavement device is selected based on the purpose: a street in a small city, a highway and a bicycle path require different asphalt. To obtain best coverage, but do not overspend materials, use the following selection principles.

Basic principles

• The grain composition of the mineral ingredient, i.e. stone, sand and powder, is the basis for ensuring the density and roughness of the coating. Most often, the principle of continuous granulometry is used, and only in the absence of coarse sand - the method of intermittent granulometry. Grain composition - particle diameters and their correct ratio, must fully comply with specifications.

The mixture is selected in such a way that the curve is placed in the area between the limit values ​​and does not include fractures: the latter means that there is an excess or deficiency of some fraction.

• Various types of asphalt can form a frame and frameless structure of the mineral component. In the first case, crushed stone is enough for the stones to come into contact with each other and form a clearly defined structure of asphalt concrete in the finished product. In the second case, stones and grains of coarse sand do not touch. A somewhat conditional boundary between the two structures is the content of crushed stone in the range of 40–45%. When choosing, this nuance must be taken into account.
• Cuboid or tetrahedral crushed stone guarantees maximum strength. This stone is the most durable.
• The surface roughness reports 50–60% of crushed stone from hard-to-polish rocks or sand from them. Such a stone retains the roughness of a natural cleavage, and this is important for ensuring asphalt shear resistance.
• In general, crushed sand asphalt is more shear resistant than quarry asphalt due to the smooth surface of the latter. For the same reasons, the durability and resistance of gravel-based material, especially marine, is less.
• Excessive grinding of mineral powder leads to an increase in porosity, and, therefore, to the consumption of bitumen. And this property has most industrial waste. To reduce the parameter, the mineral powder is activated - treated with surfactants and bitumen. This modification not only reduces the bitumen content, but also increases water and frost resistance.
• When selecting bitumen, one should be guided not only by its absolute viscosity - the higher it is, the higher the asphalt density, but also by weather conditions. So, in arid regions, a composition is selected that provides the lowest possible porosity. In cold mixes, on the contrary, the volume of bitumen is reduced by 10–15% in order to reduce the level of caking.

Line-up selection

The selection process for general view the same:

• assessment of the properties of mineral ingredients and bitumen. This refers not only to absolute indicators, but their correspondence to the final goal;
• calculate such a ratio of stone, sand and powder so that this part of the asphalt acquires the maximum possible density;
• last of all, the amount of bitumen is calculated: sufficient to ensure, on the basis of the selected materials, the desired technical properties of the finished product.

First, theoretical calculations are carried out, and then laboratory tests. First of all, the residual porosity is checked, and then the compliance of all other characteristics with the expected ones. Calculations and tests are carried out until a mixture is obtained that fully satisfies those tasks.

Like any complex building material, AB does not have unambiguous qualities - density, specific gravity, strength and so on. Its parameters determine the composition and method of preparation.

The following informative video will tell you about how the asphalt concrete composition is being designed in the USA:

3.8. It is necessary to select the composition of the fine-grained hot asphalt mix type B, grade II for dense asphalt concrete, intended for the top layer of the pavement in the III road-climatic zone.

The following materials are available:

crushed granite fraction 5-20 mm;

crushed limestone fraction 5-20 mm;

river sand;

material from screenings of granite crushing;

material from limestone crushing screenings;

mineral powder not activated;

bitumen oil grade BND 90/130 (according to the passport).

The characteristics of the tested materials are given below.

Granite crushed stone: grade for crushing strength in a cylinder - 1000, grade for wear - I-I, grade for frost resistance - Mrz25, true density - 2.70 g / cm 3;

crushed limestone: grade for crushing strength in the cylinder - 400, grade for wear - I-IV, grade for frost resistance - Mrz15, true density - 2.76 g / cm 3;

river sand: the content of dusty and clay particles - 1.8%, clay - 0.2% of the mass, the true density - 2.68 g / cm 3;

material from screenings crushing granite brand 1000:

material from crushing screenings of limestone grade 400: the content of dusty and clay particles - 12%, clay - 0.5% by weight, true density - 2.76 g/cm 3 ;

non-activated mineral powder: porosity - 33% by volume, swelling of samples from a mixture of powder with bitumen - 2% by volume, true density - 2.74 g / cm 3, bitumen capacity index - 59 g, humidity - 0.3% of the mass;

bitumen: needle penetration depth at 25°С - 94×0.1 mm, at 0°С - 31×0.1 mm, softening point - 45°С, extensibility at 25°С - 80 cm, at 0°С - 6 cm, Fraas brittle point - minus 18°C, flash point - 240°C, adhesion to the mineral part asphalt mix withstands, penetration index - minus 1.

According to the test results, granite crushed stone, river sand, material from screenings of granite crushing, mineral powder and bitumen grade BND 90/130 can be considered suitable for the preparation of mixtures of type B grade II.

Table 7

mineral material	Mass fraction, %, grains smaller than a given size, mm
Initial data
Granite crushed stone
river sand
Granite crushing screening materials
mineral powder
Estimated data
Granite crushed stone (50%)
River sand (22%)
Materials from screenings of granite crushing (20%)
Mineral powder (8%)
Requirements GOST 9128-84 for mixtures type B

Crushed limestone and material from limestone crushing screenings do not meet the requirements of Table. 10 and 11 GOST 9128-84 in terms of strength.

Grain compositions of selected mineral materials are given in tab. 7.

The calculation of the composition of the mineral part of the asphalt concrete mixture begins with the determination of such a mass ratio of crushed stone, sand and mineral powder, in which the grain composition of the mixture of these materials meets the requirements of Table. 6 GOST 9128-84.

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1 The system of regulatory documents in construction STANDARD OF THE ENTERPRISE The procedure for the selection and approval of asphalt recipes concrete mixtures STP Directorate of the Regional Road Fund Kemerovo FOREWORD

2 1. DESIGNED BY AUTONOMOUS non-profit organization"Kuzbassdorertification" (candidate of technical sciences, associate professor O.P. Afinogenov, engineer V.B. Sadkov). 2. INTRODUCED by the Autonomous non-profit organization "Kuzbassdorsertifikatsiya". 3. APPROVED and put into effect by the State Institution "Kemerovo Directorate of the Regional Road Fund". 4. INTRODUCED FOR THE FIRST TIME. State institution "Kemerovo dir. reg.dor. fund”, 2000 Standard of the enterprise The procedure for the selection and coordination of recipes for asphalt concrete mixtures Introduced for the first time Approved and put into effect by order of March 13, 2001, 31

3 1. SCOPE Date of introduction This standard establishes the basic requirements for the procedure for selecting recipes for asphalt concrete mixtures, the procedure for their coordination when performing road works under contracts with the State Institution "Kemerovo Regional Road Fund Directorate" (hereinafter the customer, State Institution "Kemerovo DODF"). 2. REGULATORY REFERENCES This standard uses references to the following regulatory documents: SNiP System of regulatory documents in construction. Basic provisions; SNiP Highways; SNiP *. Organization of construction production; GOST Testing and product quality control. Basic terms and definitions; GOST Asphalt concrete mixes for road, airfield and asphalt concrete; GOST Materials based on organic binders for road and airfield construction. Test methods; STP Preparation of road bitumen modified with atactic polypropylene. Standard regulation; Specifications Road bitumens modified with atactic polypropylene. 3. DEFINITIONS 3.1. This standard uses terms and their definitions corresponding to GOST 9128, GOST 16504, SNiP, SNiP Asphalt concrete mixture rationally selected mixture of mineral materials (crushed stone [gravel] and sand with or without mineral powder) with bitumen, taken in certain proportions and mixed in heated state. Asphalt concrete is a compacted asphalt mix. A recipe for an asphalt concrete mixture is a document that is part of the technological regulations, containing information characterizing the scope of the mixture, its composition and physical and mechanical properties, consumption of materials; approved and agreed in the prescribed manner. 4. GENERAL PROVISIONS

4 4.1. The contractor does not have the right to perform work using asphalt concrete mixtures at the facilities of Kemerovo DODF without recipes for their production, agreed in the manner regulated by this standard. The recipe is drawn up for the construction season, for each mixture used at this facility. It is allowed to issue one recipe for several objects of the same type. If the recipe is adjusted based on the results of production control, when replacing materials, etc., the recipe is subject to re-approval in the manner prescribed by section The recipe must comply with the requirements of project documentation, SNiP, GOST, other regulatory documents ( VSN, OST, STP, etc.) The selection of the composition of the asphalt concrete mix should be carried out by an organization that has a competent laboratory and guarantees the reliability of the test results and the completeness of the controlled features (characteristics) of the asphalt mix. ) duly recognized laboratory accreditation system, or having a certificate of official assessment of the state of measurements according to MI These properties The selection (design) of the mixture consists of five stages: 1) establishing the requirements for the mixture; 2) selection of materials and assessment of their suitability; 3) determination of a rational quantitative ratio of the components of the mixture; 4) quality control of the composition; 5) economic assessment of the quality of the composition Assignment for the design of the asphalt mix is ​​issued by the chief engineer of the contracting organization. The mixture can be selected by the contractor's road construction laboratory or a laboratory involved from outside. The assignment for the design of the mixture should specify: type of asphalt mix (hot, cold, coarse, fine, sandy); type of asphalt concrete (high-density, dense, porous, highly porous); type of mixture and grade of asphalt concrete; Desirable Materials When designing asphalt mixes, one should aim for the most economical mix. 5. DESIGNATION OF MAIN PARAMETERS OF THE MIXTURE 5.1. The main parameters and type of mixture (asphalt concrete) are assigned according to the project documentation. If at the same time deviations from the requirements of the normative documents in force at the time of selection of the mixture are found, it is necessary to coordinate the parameters with the customer. Asphalt mixes should

5 apply in accordance with p SNiP, adj. A GOST and meet the requirements of GOST The customer has the right to set higher rates of asphalt concrete mixture (asphalt concrete) than provided for by SNiP (with appropriate compensation for the contractor's costs) reliable adhesion to top layer) and high shear stability highways In areas with heavy traffic, hot high-density mixtures of type A should be used. To repair minor damage to asphalt concrete pavements, mixtures are used that are similar in properties to mixtures of the repaired layer of the coating layer. 6. SELECTION OF MIXTURE COMPONENTS 6.1. The materials used for the preparation of asphalt concrete mixtures must comply with the requirements of GOST. It is advisable to use crushed stone from igneous or metamorphic basic and carbonate rocks, which have better adhesion to petroleum bitumen. The shape of the crushed stone should approach the cube and not have flat flaky grains. Gravel is a less desirable component, as it has smooth surface, inclusions of weak rocks. An increase in the amount of crushed stone increases the crack resistance and shear resistance of coatings It is desirable to use sand consisting of particles different sizes. One-size sand increases the porosity of the mineral part. Sand from crushing screenings contributes to an increase in the internal friction of the mineral part due to the content of acute-angled grains in it. River sand is not recommended. Mineral powders obtained by artificial grinding of limestones and dolomites should be used for asphalt concrete mixtures. The presence of very fine clay particles in the mineral powder increases the swelling of asphalt concrete when wet, increases the bitumen content of the mixture. A large number of particles larger than 0.071 mm increases the consumption of mineral powder and complicates the process of preparing and laying the mixture. The properties of the binder largely determine the quality of asphalt concrete. Excessive viscosity of bitumen leads to the formation of cracks when low temperatures, and low viscosity to plastic deformation of coatings in hot weather. In accordance with the requirements of SNiP in the conditions of the Kemerovo region, it is necessary to use polymer-bitumen binders (modified bitumens). For modification, a polymer-bitumen binder of the PBV, "Kaudest-D" grades, a bitumen-rubber binder of the BKV grades are used;

6 modified with atactic polypropylene, carried out according to STP Polymer additives increase bitumen elasticity, its thermal stability in a wide temperature range, strength and corrosion resistance of asphalt concrete. It should be borne in mind that with a lack or excess of bitumen, the mechanical strength of concrete decreases. With an increase in the amount of bitumen, the water resistance of asphalt concrete increases due to a more complete envelopment of stone materials with a bituminous film and filling of pores, and the heat resistance decreases. With a decrease in the amount of bitumen, the opposite phenomenon is observed: water saturation increases, water resistance decreases, and heat resistance increases, concrete becomes more rigid and brittle. 7. CALCULATION OF MIXTURE COMPOSITION 7.1. The design of the composition of the asphalt concrete mixture (asphalt concrete) is allowed to be carried out according to any known method. It is recommended to use the SoyuzdorNII method, which GOST is focused on. The basis of the method is the assumption that the strength of concrete is determined by its structure and is ensured by the creation of a dense mineral mixture with the optimal amount of bitumen use mixtures of types A and B Calculation of asphalt concrete includes two stages: calculation of the granulometric (grain) composition of the mineral part of the mixture from a given set of materials according to the tables of granulometric composition (Tables 2 and 3 GOST); experimental definition physical and mechanical parameters of asphalt concrete, assessment of their compliance with GOST requirements, as well as selection of the optimal amount of bitumen by testing test samples with the same composition of stone materials and different bitumen content. The criterion for determining the optimal amount of bitumen is the best correspondence between water saturation and mechanical compressive strength at a temperature of 20 C and 50 С test samples corresponding to the requirements of GOST EXAMPLE OF CALCULATION OF THE COMPOSITION OF A FINE-GRAINED MIXTURE 8.1. Task: Calculate the composition of fine-grained hot asphalt concrete type B, grade II. Constituent materials: Crushed stone of the Mozzhukhinsky quarry, fractions 5-20 mm; Sand of the Yaya plant building materials;

7 Limestone mineral powder. Calculation procedure. Based on the limits of the required granulometric compositions (Table 3 GOST) and the results of sieving the mineral materials used (Table 1), we determine the approximate percentage of each material (crushed stone, sand, mineral powder). Table 1 Name of material, manufacturer or quarry Partial residues (number of grains, % by weight, less than those left on a sieve with mesh size, mm) .5 1.25 0.63 0.315 0.14 0.071 less KSM Mineral powder 5.3 33.7 30.2 23.6 3.7 3.5 1.0 18.5 17.0 7.5 12.4 24.6 8.8 4.2 6.0 1, 2 2.0 8.6 16.6 71.6 Crushed stone content X a 45 = 100 = 100 = 48.49% b 92.8 3 GOST; b fraction content larger than 5 mm in crushed stone. Mineral powder content a1 6 Z = 100 = 100 = 8.4% b 71.6 1 b1 fraction content smaller than 0.071 mm in mineral powder. Considering the presence of grains larger than 5 mm and smaller than 0.071 mm in the sand, we reduce the values ​​obtained above for the content of crushed stone and mineral powder in the mixture to the following values: crushed stone 42.0%, mineral powder 7.0%. Then the content of sand in the mixture Fill in table 2. Y = 100 (x + z); Y \u003d 100 (42 + 7) \u003d 51%

8 Comparison of the data in column 10 with the data in column 11 indicates that the composition of the designed mineral part of the asphalt concrete mixture corresponds to the required compositions of dense mixtures. Table 2 Calculation table for determining the total residues of the designed mineral mixture The size of the sieve openings in mm Granulometric composition of the constituent materials in % crushed stone sand mineral powder The granulometric composition of materials in the designed mixture in % crushed stone sand mineral powder Partial residues of the designed mineral mixture in % in % Total passages Permissible limits of total passages according to GOST,3 2.2 2.2 2.2 97.7 14.2 14.2 16.4 83.2 1.0 12.6 0.5 13.1 29, 5 70.6 18.5 9.9 9.4 19.3 48.8 51.5 3.7 17.0 1.6 8.7 10.3 59.1 40.25 3.5 7.5 1 .5 3.8 5.3 64.4 36.63 12.4 1.2 6.3 0.1 6.4 70.8 29.315 24.6 2.0 12.5 0.1 12.6 83, 4 16.14 8.8 8.6 4.6 0.6 5.2 88.6 11.071 4.2 16.6 2.1 1.2 3.3 91.9 8. Less than 6.0 71.6 3.1 5.0 8, We determine the percentage of bitumen in accordance with the recommendations of Annex G GOST, it is 5.0-6.5%. Based on this, we prepare three asphalt concrete mixtures with the same mineral composition and the estimated amount of bitumen (5.0-5.8-6.5%). Test samples are made from these compositions, which are tested for compression at a temperature of +20 and +50 C and for water saturation. The optimal amount of bitumen is taken to be the content at which the best performance asphalt concrete. We produce control samples of the designed composition with the optimal amount of bitumen and subject them to a full cycle of tests. The test results are entered in Table 3. Table 3 Indicators of asphalt concrete properties

9 Indicator name GOST requirements Actual indicators Indicator name GOST requirements Actual indicators Average density, 2.38 Water resistance at g/cm 3 long-term water saturation Porosity of the mineral part by volume, % Residual porosity, % 19 16.3 Cohesion of bitumen with the mineral part 2.5 5.0 3.4 Shear stability index Water saturation, % 1.5 4 .0 2.8 Crack resistance index Compressive strength at temperature, MPa Total specific effective activity of natural radionuclides, Bq/kg 0.75 0.87 Passes Passes C 2.2 2.6 50 C 1.0 1.1 0 C 12.0 10.0 Water resistance 0.85 0.93 Shear resistance and crack resistance are determined if they are standardized by the design documentation for the construction of asphalt concrete pavement. We calculate the composition of the asphalt concrete mixture for one batch of the mixer. The initial data are the mass of the batch and the cell sizes of the sieves of the screen of hot materials installed at the asphalt plant. For ABZ DS, the mass of the batch is 600 kg, sieves with cells of 5, 15, 35 mm are installed on the screen. The mass of material to be supplied from the hopper for batching is equal to (F1 F2) 600 D i =, 100 B where i is the number of the hopper from which the material for batching is taken; F1 total residue on the underlying sieve in%, is taken according to the data in Table. 2; F2 total residue on the overlying sieve in%, taken according to the table. 2; 600 batch mass, kg; B percentage of bitumen in the mixture;

10 (100 48.8) 600 D 0 5 = = 289.8 kg; 100 1.06 (48.8 16.4) 600 D 5 15 = = 183.4 kg 100 1.06 (16.4 0) 600 D = = 92.8 kg.06; Since the mineral powder is fed through a separate supply line, it is necessary to subtract the mass of the mineral powder "289, D 0 5 = = 289.6 39.6 = 250 kg; 100 1.06 from the mass of material shipped from the D0-5 hopper. Calculation results enter in table 4. The composition of the asphalt concrete mixture Binder or fractions of stone materials in accordance with Dosage for batching 600 kg with hot bunkers ABZ 1 Fraction mm 92.8 2 Fraction 5-15 mm 183.4 3 Fraction 0-5 mm 250.0 4 Mineral powder 39.6 5 Bitumen 34.2 of asphalt concrete mixture, t; H thickness of the layer, m; S area of ​​the layer, equal to 1000 m2; G average density of asphalt concrete, from Table 3, t/m3. this is 3% of the volume of asphalt concrete. V "W 100 \u003d P (100 + C),

11 where V "consumption of inert stone materials, m 3; W percentage this material in the mixture; P volume-bulk mass of stone materials; C percentage of bitumen in the mixture. "V 1 = = 28.5 m 1.39 () " V 2 = = 33.0 m 1.46 () Consumption of materials 3 3; ; Table 5 Per 100 t mixture Per 1000 m 2 coating Name of material Bulk density, t / m 3 Content in the mixture in% T M 3 Crushed stone 1.5 Mozzhukhinsky quarry Sand Yaya KSM 1, Mineral powder 7 6.6 Bitumen 6 5.7 Asphalt concrete mix (t), at layer thickness,2 9. DESIGN OF MIXTURE RECIPES 9.1. For each mixture, a separate recipe is drawn up, which must have an individual number, consisting of a serial number in a given year and two last digits year for which it was drawn up (for example, 14-00). Ordinal numbers must correspond to the registration numbers according to the "Journal for determining the physical and mechanical properties of asphalt concrete mixtures in the selection of compositions and periodic quality control of the produced asphalt concrete mixture" (form D-7) Recipes are drawn up on standard forms, in the form given in the appendix. All entries must be clear and accurate, no strikethrough of the text, blots are allowed. The following design options are allowed: using a personal computer; on the form by hand, in ink (paste) in black or blue. The second and third copies of the prescription may be photocopies. For examination and approval, 3 copies of the recipe approved by the chief engineer (technical director) of the organization are submitted (indicating the date of approval, last name, initials of the approver, name of the contractor. The signature is certified with a seal.

12 It is forbidden to submit photocopies of prescriptions where the signature and seal are copied The organization performing the examination, the customer have the right not to consider prescriptions drawn up in violation of the requirements structural element , in which the mixture is used (top, bottom layer of coating, base), type, type and brand of mixture (asphalt concrete), object, for example: "... for the installation of the top layer of the coating (hot, type A, grade I) on a highway "Novosibirsk - Irkutsk", km 45-60 "The recipe must contain: information about the mineral materials used, the grain composition of the mixture (with and without division into constituent materials), binder; production recipe; indicators of the properties of the mixture and asphalt concrete; material consumption data. The norms of hard-to-remove losses taken into account in the recipe should be indicated. For installations such as DS-117, DS-158, the loss rate for asphalt concrete is 1.5%, the loss rate for laying the mixture is 1.5% The recipe must be signed by the head of the laboratory that performed the selection. If the selection is made by a third-party organization, the recipe is signed by its technical manager, the signature is certified by a seal. 10. APPROVAL AND APPROVAL OF THE RECIPE The recipe for the asphalt mix used at the facilities of the State Institution "Kemerovo DODF" must be approved by the chief engineer (technical director) of the contracting organization and agreed by the chief engineer of the customer (GU "Kemerovo DODF"). If the contracting organization purchases the mixture from a third party, it is obliged to ensure that the mixture complies with the recipe approved by the State Institution "Kemerovo DODF". Before the recipe is approved by the customer, he must undergo an examination at the Kuzbass Center for Road Research LLC. The examination must be carried out within a period of not more than 5 working days. In the process of examination, the compliance of the recipe with the requirements of SNiP, GOST 9128, the correctness of its execution and calculation of the composition of the mixture are assessed. Compliance of the physical and mechanical and other parameters of the mixture specified in the recipe with the actual values ​​is controlled during the technical supervision of the customer. The contractor is responsible for the accuracy of the information provided in the recipe and the compliance of the mixtures used with the recipes. The customer is obliged to review the recipe submitted for approval within 5 days. If the recipe has gone through the approval procedure, one copy of it remains with the customer, one copy is sent to the contractor and the organization exercising independent control. In case of refusal to agree, the customer sends the prescription to the contractor. Refusal must be motivated. After the appropriate adjustment, the recipe again goes through the approval procedure provided for by this standard Reasons for refusal to approve the recipe: - the recipe did not pass the examination; - non-compliance with the requirements of regulatory documents and (or) the project;

13 - non-compliance with the requirements of this standard. 11. INSPECTION CONTROL OVER COMPLIANCE WITH MIXTURE RECIPES Inspection control over compliance with asphalt mix recipes is carried out by the customer's technical supervision service engineers, an independent competent organization (on behalf of the customer), the administration of the organization producing the mixture or using it. AGREED Chief Engineer of KDODF A.S. Belokobylsky 200 M.P. I APPROVE Chief Engineer 200 M.P. RECIPE of asphalt concrete mix for the device (type and type brand) (upper / lower / coating layer, base) on the road from PC (km) to PC (km) Name of material, 1. APPLIED MINERAL MATERIALS weight remaining on a sieve with a mesh size, mm)

14 manufacturer or quarry Name of material,5 1.25 0.63 0.315 0.14 0.071 less 2. GRAIN COMPOSITION OF ASPHALT CONCRETE MIXTURE 2.1. Divided into constituent materials Content Partial residues (number of grains, % by weight, remaining on a sieve with mesh size, mm) in a/b.5 1.25 0.63 0.315 0.14 0.071 less mixture, e % 2.2. Without dividing into constituent materials Partial residues, % Total residues, % Passages, % Grain composition of the mineral part of the mixture according to GOST, % 3. BINDER, % over 100% of the mineral part 3.1. Bitumen (brand, manufacturer) content in binder, % 3.2. Modifier (name, brand) content in binder, % 3.3. Solvent (name, brand,) content in the binder, % Binder or fractions of stone materials in accordance with the hot bunkers of ABZ kg Name of indicators 5. INDICATORS OF ASPHALT CONCRETE PROPERTIES ACCORDING TO GOST Actually Name of indicators According to GOST Actually

15 1. Average density, g / cm 3 6. Water resistance during long-term water saturation 2. Porosity of the mineral part,% by volume 3. Water saturation,% by volume 4. Compressive strength (MPa) at: 20 C 50 C 0 C 5 Water resistance 7. Adhesion of bitumen with the mineral part of the asphalt mix 8*. Shear stability index 9*. Crack resistance index 10. Total specific effective activity of natural radionuclides Passes the test * These indicators are determined if they are normalized by the design documentation for the construction of the coating 6. MATERIAL CONSUMPTION Bulk density, t / m 3 T Content Name of the material in the mixture,% M 3 Per 100 tons of mixture Bq/kg Per 1000 m 2 pavement Asphalt-concrete mixture (t), with a layer thickness of 4 cm When changing the layer thickness by 0.5 cm, add The table is compiled taking into account the loss rate % for asphalt concrete and % for laying the mixture. Head of the SL that performed the selection Approved by KuzTsDI

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Master's degree

O.A. KISELEVA

CALCULATION OF COMPOSITION OF ASPHALT CONCRETE MIXTURE

For undergraduates studying in the direction 270100

"Construction", guidelines for settlement and graphic work

in the discipline "Physical foundations for the design of new construction

materials"

Approved by the Editorial and Publishing Council of TSTU

Printed version of the electronic edition

Tambov

RIS TSTU

UDC 625.855.3(076)

BBK 0311-033ya73-5

Compiled by: Ph.D., Assoc. O. A. Kiseleva

Reviewer: Doctor of Technical Sciences, prof. Ledenev V.I.

Calculation of the composition of the asphalt concrete mixture: Metod.ukaz. / Comp.: O.A. Kiseleva. Tambov: TSTU, 2010 - 16 p.

Guidelines for the implementation of settlement and graphic work on the discipline "Physical foundations for the design of new building materials" for undergraduates studying in the direction 270100 "Construction".

Approved by the editorial and publishing board of the Tambov State Technical University

© GOU VPO "Tambov State

Technical University (TSTU), 2010

INTRODUCTION

Guidelines are devoted to the selection of the composition of asphalt concrete.

To design the composition of asphalt concrete, you need to know the following:

– grain composition of aggregates,

- brand of bitumen,

- brand of asphalt concrete.

The calculation of the composition of asphalt concrete consists in choosing a rational ratio between the constituent materials, which ensures the optimal density of the mineral core with the required amount of bitumen and obtaining concrete with the given technical properties with a certain production technology.

METHODS FOR CALCULATION OF THE COMPOSITION OF ASPHALT CONCRETE MIXTURE

The most widely used method of calculation from the curves of dense mixtures. It states that the greatest strength of concrete is achieved under the condition of the maximum density of the mineral composition by calculating the particle size distribution and determining the content of the optimal amount of bitumen and mineral powder.

The calculation of the composition of asphalt concrete includes the following steps:

– calculation of the granulometric composition of the mineral mixture according to the principle of minimum voids,

– determination of the optimal amount of bitumen,

– determination of the physical and mechanical properties of the calculated mixtures,

- making adjustments to the obtained compositions of mixtures.

1.Calculation of the granulometric composition of the mineral mixture . For this purpose, for fine and coarse aggregate, according to data on partial residues on sieves, residuals A i , % are found equal to the sum of partial residues (а i) on a given sieve and on all sieves smaller than this . The results obtained, taking into account the grade of asphalt concrete in terms of aggregate size, are entered in Table 1.

2.We determine the amount of aggregate by fractions. The calculation is performed according to the limit curves corresponding to the selected runoff coefficients (Fig. 1) . Curves with a runoff coefficient of less than 0.7 are attributed to the compositions of the mineral part of the asphalt concrete mixture with a low content of mineral powder. Compositions calculated by a runoff factor of 0.9 contain an increased amount of mineral powder.

For this purpose, depending on the brand of asphalt concrete, the required amount of sand is determined on a sieve with a mesh size of 1.25 or crushed stone on a sieve with a mesh size of 5 mm (for fine-grained asphalt concrete). For example, for coarse-grained asphalt concrete, the amount of sand particles finer than 1.25 mm is in the range from 23 to 46%. We accept 40%. After that, we determine the coefficient for adjusting the grain composition of sand

Table 1

Granulometric composition of the mineral mixture

Filler type	Remains	Sieve opening sizes
			2,5	1,25	0,63	0,315	0,14	0,07
rubble	a i	a 20 u	a 10 u	a 5 u
A i	A 20	A 10	A 5
Sand	a i				a 2.5 p	a 1.25 p	a 0.63 p	a 0.315 p	a 0.14 p
A i				A 2.5 p	A 1.25 p	A 0.63 p	A 0.315 p	A 0.14 p
mineral powder	a i						a 0.63 m	a 0.315 m	a 0.14 m	a 0.07 m
A i						A 0.63 m	A 0.315 m	A 0.14 m	A 0.07 m

The required amount of mineral powder is determined on a sieve with a mesh size of 0.071. For coarse-grained asphalt concrete, the amount of particles smaller than 0.071 mm is in the range from 4 to 18%. We accept 10%. After that, we determine the coefficient for adjusting the grain composition of the mineral powder .

We determine the coefficient for adjusting the grain composition of crushed stone (or sand) . And we specify the grain composition of aggregates (Table 2).

Table 2

Estimated composition of aggregates

Filler type	Remains	Sieve opening sizes
			2,5	1,25	0,63	0,315	0,14	0,07
rubble	a i	K w × a 20 w	K w × a 10 w	K u × a 5 u
A i
Sand	a i				K p × a 2.5 p	K p × a 1.25 p	K p × a 0.63 p	K p × a 0.315 p	K p × a 0.14 p
A i
mineral powder	a i						K m × a 0.63 m	K m × a 0.315 m	K m × a 0.14 m	K m × a 0.07 m
A i
∑A

Based on the data obtained, a particle size distribution curve of a specific calculated mixture is constructed, which should be located between the limit runoff curves. We specify the number of filler components by fractions, taking into account the type of asphalt concrete according to Table 3.

Table 3

Optimal granulometric composition of the mineral mixture

Mix type	Grain content of mineral material, %, finer than given size, mm	Approximate consumption of bitumen, % by weight
				2,5	1,25	0,63	0,315	0,14	0,071
Blends of continuous granulometry
Medium grain types: A B C	95-100 95-100 95-100	78-85 85-91 91-96	60-70 70-80 81-90	35-50 50-65 65-80	26-40 40-55 55-70	17-28 28-39 39-53	12-20 20-29 29-40	9-15 14-22 20-28	6-10 9-15 12-19	4-8 6-10 8-12	5-6,5 5-6,5 6,5-7
Fine-grained types: A B C		95-100 95-100 95-100	63-75 75-85 85-93	35-50 50-65 65-80	26-40 40-55 57-70	17-28 29-39 39-53	12-20 20-29 29-40	9-15 14-22 20-28	6-10 9-15 12-19	4-8 6-10 8-12	5-6,5 5,5-7 6-7,5
Sand types: D				95-100 95-100	75-88 80-95	45-67 53-86	28-60 37-75	18-35 27-55	11-23 17-55	8-14 10-16	7,5-9 7-9
Discontinuous granulometry blends
Medium grain types: A B	95-100 95-100	78-85 85-91	60-70 70-80	35-50 50-65	35-50 50-65	35-50 50-65	35-50 50-65	17-28 28-40	8-14 14-22	4-8 6-10	5-6,5 5-6,5

T a b l e 3 continued

3.We determine the consumption of bitumen. It is promising to calculate the amount of bitumen in the mixture according to the method developed by HADI and based on the bitumen content of mineral components. The calculation is carried out in two stages: determination of the bitumen capacity of each fraction of the mineral part of the mixture and calculation of the bitumen content. To determine the bitumen content, dried materials are dispersed into fractions less than 0.071, 0.071-0.14, 0.14-0.315, 0.315-0.63, 0.63-1.25, 1.25-3, 3-5, 5-10 mm etc. to the largest gravel size. The bitumen capacity of each fraction is presented in table 4. We determine the content of bitumen for each fraction (table 5).

Table 4

Bitumen capacity of the filler

Fraction size, mm	Bitumen content, %
granite material	Diorite material	Dense, durable limestone material	Pure rounded quartz sand and gravel
20-40	3,9	3,3	2,9	–
10-20	4,7		3,5	–
5-10	5,4	4,5	4,1	2,8
2,5-5	5,6	5,6	4,6	3,3
1,25-2,5	5,7	5,9	5,3	3,8
0,63-1,25	5,9		6,0	4,6
0,315-0,63	6,4	7,9	7,0	4,8
0,14-0,315	7,4		7,3	6,1
0,071-0,14	8,4		9,4
0,071		16,5

T a b l e 5

Determination of bitumen content

T a b l e 6

Physical and mechanical characteristics of asphalt concrete

Indicators	Norms for mixtures for the top layer	Norms for the mixture for the bottom layer
1st mark	II mark
Porosity of the mineral core, % by volume for mixtures of types: A (multi-crushed stone, crushed stone 50-65%) B (medium crushed stone, crushed stone 35-50%) C (small crushed stone, crushed stone 20-35%) D (sandy from crushed sand with a fraction content 1.25-5 mm >33%) D (sandy from natural sand)	15-19 15-19 18-22 – –	15-19 15-19 18-22 18-22	16-22
Residual porosity, % by volume	3-5	3-5	5-10
Water saturation, % by volume for mixtures: A B and D C and E	2-5 2-3,5 1,5-3	2-5 2-3,5 1,5-3	3-8
Swelling, % by volume, no more	0,5		1,5
Compressive strength, kgf / cm 2 for mixtures of types at temperatures of 20-50 0 C: A B and D C and D at a temperature of 0 0 C	–		–
Water resistance coefficient, not less than	0,9	0,85	–
Water resistance coefficient at long-term water saturation, not less than	0,8	0,75	–

The optimal content of bitumen in the mixture is determined by the following formula

where K is a coefficient depending on the brand of bitumen (for BND 60/90 - 1.05; BND 90/130 - 1; BND 130/200 - 0.95; BND 200/300 - 0.9); B i – bitumen capacity of fraction i; P i is the content of fraction i in the mixture in parts of the whole.

4. From table 6 we write out the physical and mechanical parameters characteristic of this asphalt concrete.

CALCULATION EXAMPLE

Select the composition of fine-grained asphalt concrete type A. Fillers: crushed granite, quartz sand, a mineral powder obtained by grinding diorite.

The calculation of total balances is presented in Table 7.

Table 7

private remains

Filler type	Remains	Sieve opening sizes
				2,5	1,25	0,63	0,315	0,14	0,071
rubble	a i
A i
Sand	a i
A i
mineral powder	a i
A i

Since the crushed stone is fine-grained, it is sieved through a sieve with a mesh size of 5 mm, and larger fractions are removed.

We determine the amount of aggregate by fractions. For fine-grained asphalt concrete, the amount of crushed stone particles smaller than 5 mm is in the range from 84 to 70%. We accept the required content of crushed stone larger than 5 mm 25%. We determine the coefficient for adjusting the grain composition of crushed stone K u = 25 * 100 / (100-28) = 34.7.

The required amount of mineral powder on a sieve with a mesh size of 0.071 is in the range from 10 to 25%. We accept 15%. The coefficient for adjusting the grain composition of the mineral powder is K m =15*100/74=27.7.

We determine the coefficient for adjusting the grain composition of sand K p \u003d 100-35-28 \u003d 37.

We specify the grain composition of aggregates, taking into account the grade of asphalt concrete by the size of the aggregate (table 8).

Table 8

Grain composition of aggregates

Filler type	Remains	Sieve opening sizes
			2,5	1,25	0,63	0,315	0,14	0,071
rubble	a i			28*0,35=9,8
A i			9,8
Sand	a i				16*0,37=5,9	22*0,37=8,2	20*0,37=7,4	30*0,37=11,1	12*0,37=4,4
A i					31,1	22,9	15,5	4,4
mineral powder	a i						7*0,28=2	10*0,28=2,8	9*0,28= 2,5	74*0,28=20,7
A i								23,2	20,7
∑A			74,8		59,1	50,9	41,5	27,6	20,7

We check the correctness of the choice of the grain composition of the mineral mixture. To do this, we build a graph of particle size distribution and apply it to the run-off curves (Fig. 5). It can be seen from the figure that the graph is included in the allowable area. The calculation is correct.

Knowing the bitumen capacity of individual fractions, we determine the bitumen consumption (table 9).

We determine the estimated content of bitumen grade BND 90/130 B = 1 * 6.71 = 6.71%. We check the content of bitumen according to the table. 3. Since the amount of bitumen according to the calculation is more than the normative 5-6.5%, we accept B = 6.71%.

We write out the physical and mechanical parameters characteristic of this asphalt concrete:

- porosity of the mineral core -18-22%,

– residual porosity – 3-5%,

- water saturation - 1.5-3%,

– swelling – 0.5%,

- compressive strength - 10 kgf / cm 2,

– coefficient of water resistance – 0.9,

- coefficient of water resistance with long-term water saturation - 0.8.

Table 9

Determination of bitumen content

Fraction size	Private balances (in fractions of a unit)	Bitumen content, % (from Table 4)	Total bitumen content, %
rubble	Sand	mineral powder	rubble	Sand	mineral powder
2,5-5	0,098			4,6			0,45
1,25-2,5		0,059			3,8		0,22
0,63-1,25		0,082			4,6		0,38
0,315-0,63		0,074	0,02		4,8	7,9	0,36+0,16
0,14-0,315		0,111	0,028		6,1	9,0	0,68+0,25
0,071-0,14		0,044	0,025			19,0	0,31+0,48
0,071			0,207			16,5	3,42
Bitumen content=∑	6,71

BIBLIOGRAPHY

1. Glushko I.M. Road building materials. Textbook for automobile and road institutes / Glushko I.M., Korolev I.V., Borshch I.M. and others. - M. 1983.

2. Gorelyshev N.V. Materials and products for the construction of roads. Directory. / Gorelyshev N.V., Guryachkov I.L., Pinus E.R. and others - M .: Transport, 1986. - 288 p.

3. Korchagina O.A. Calculation of the composition of concrete mixtures: Method. decree / Korchagina O.A., Odnolko V.G. - Tambov: TSTU, 1996. - 28 p.

T a b l e P 1

Data for the task

Option	Type of asphalt concrete	Type of asphalt concrete	Type of asphalt concrete by production method	Appointment of asphalt concrete	BND bitumen grade
	coarse-grained	BUT	hot	Top Coat	60/90
	medium-grained	B	warm	bottom cover	90/130
	fine-grained	AT	hot	Top Coat	130/200
	sandy	G	cold	bottom cover	200/300
	coarse-grained	B	warm	Top Coat	60/90
	medium-grained	AT	cold	bottom cover	130/200
	fine-grained	BUT	warm	bottom cover	90/130
	sandy	D	hot	Top Coat	60/90
	coarse-grained	AT	hot	bottom cover	90/130
	medium-grained	BUT	warm	Top Coat	60/90
	fine-grained	B	cold	bottom cover	200/300
	coarse-grained	BUT	warm	bottom cover	90/130
	medium-grained	B	hot	Top Coat	60/90
	fine-grained	AT	cold	Top Coat	130/200
	sandy	G	warm	bottom cover	90/130
	coarse-grained	B	cold	Top Coat	200/300
	medium-grained	AT	hot	bottom cover	90/130
	fine-grained	BUT	warm	bottom cover	60/90
	sandy	D	cold	Top Coat	130/200
	coarse-grained	AT	cold	Top Coat	200/300
	medium-grained	BUT	warm	bottom cover	90/130
	fine-grained	B	hot	Top Coat	60/90
	sandy	D	warm	bottom cover	90/130
	coarse-grained	BUT	hot	bottom cover	60/90
	medium-grained	B	cold	Top Coat	130/200

T a b l e P 2

Data for the task

Option	Granulometry	filler material
rubble	sand	mineral powder
	continuous	granite	quartz	diorite
	continuous	diorite	quartz	diorite
	continuous	gravel	limestone	granite
	continuous	–	limestone	limestone
	intermittent	diorite	limestone	granite
	continuous	granite	quartz	limestone
	continuous	gravel	quartz	diorite
	continuous	–	limestone	diorite
	continuous	gravel	quartz	limestone
	continuous	diorite	limestone	limestone
	continuous	granite	quartz	granite
	intermittent	diorite	quartz	limestone
	continuous	gravel	limestone	limestone
	continuous	granite	limestone	limestone
	continuous	–	quartz	diorite
	continuous	gravel	quartz	granite
	continuous	granite	limestone	diorite
	continuous	diorite	limestone	diorite
	continuous	–	quartz	granite
	intermittent	granite	limestone	granite
	continuous	gravel	quartz	diorite
	continuous	diorite	quartz	granite
	continuous	–	quartz	limestone
	continuous	gravel	limestone	diorite
	intermittent	diorite	quartz	granite

The most used road building material in the 20th century - asphalt - is divided into many types, grades and types. The basis for separation is not only and not so much the list of initial components included in the asphalt concrete mixture, but the ratio of their mass fractions in the composition, as well as some characteristics of the components - in particular, the size of the sand and crushed stone fractions, the degree of purification of the mineral powder and all the same sand.

Asphalt composition

Asphalt of any type and brand contains sand, crushed stone or gravel, mineral powder and bitumen. However, as for crushed stone, it is not used in the preparation of some types of paving - but if asphalting of territories is carried out taking into account high traffic and strong short-term loads on the pavement, then crushed stone (or gravel) is necessary - as a frame-forming protective element.

mineral powder- an obligatory initial element for preparation of asphalt of any brands and types. Usually, mass fraction powder - and it is obtained by crushing rocks in which a high content of carbon compounds (in other words, from limestone and other organic fossilized deposits) - is determined based on the tasks and requirements for the viscosity of the material. A large percentage of mineral powders makes it possible to use it in such works as asphalting roads and sites: a viscous (that is, durable) material will successfully dampen the internal vibrations of bridge structures without cracking.

Most types and grades of asphalt use sand- the exception, as we said, is the types of pavement, where a large mass fraction gravel. The quality of sand is determined not only by the degree of its purification, but also by the method of obtaining: mined open way sand, as a rule, needs to be thoroughly cleaned, but artificial sand, obtained by crushing rocks, is considered ready for work.

Finally, bitumen is the cornerstone of the paving industry. A product of oil refining, bitumen is contained in a mixture of any brand in a very small amount - its mass fraction in most varieties hardly reaches 4-5 percent. Although widely used in such works as asphalting territories with complex reliefs and road repair, cast asphalt boasts a bitumen content of 10 percent or more. Bitumen gives such a canvas a fair elasticity after hardening and fluidity, which makes it easy to distribute ready mix by site.

Grades and types of asphalt

Depending on the percentage in the composition of the listed components, there are three grades of asphalt. Technical characteristics, scope and composition of the mixture of various grades are described in GOST 9128-2009, which, among other things, takes into account the possibility of adding additional additives that increase frost resistance, hydrophobicity, flexibility or wear resistance of the coating.

Depending on the percentage of the filler in the composition of the road-building mixture, it is divided into the following types:

• A - 50-60% crushed stone;
• B - 40-50% crushed stone or gravel;
• B - 30-40% crushed stone or gravel;
• G - up to 30% of sand from crushing screenings;
• D - up to 70% sand or mixtures with crushing screenings.

Asphalt grade 1

This brand produces a wide range various types coatings - from dense to highly porous, with a significant content of crushed stone. The scope of their use - road construction and landscaping: that's just porous materials are not at all suitable for the role of the actual coating, the top layer of the roadway. It is much better to use them for arranging foundations, leveling the base for laying denser types of material.

Asphalt grade 2

The density range is about the same, but the content and percentage of sand and gravel can vary quite widely. This is the same “average” asphalt, with a very wide scope: and the construction of roads, and their repair, and the arrangement of territories for parking lots and squares cannot do without it.

Asphalt grade 3

Grade 3 coatings are distinguished by the fact that crushed stone or gravel is not used in their manufacture - they are replaced by mineral powders and high-quality sand obtained by crushing hard rocks.

The ratio of sand and crushed stone (gravel)

The ratio of sand to gravel content is one of key indicators, which determines the scope of a particular type of coating. Depending on the prevalence of one or another material it is denoted by letters from A to D: A - more than half consists of fine crushed stone or gravel, and D - approximately 70 percent consists of sand (although sand is used mostly from crushed rocks).

The ratio of bitumen and mineral components

No less important - after all, it determines the strength characteristics of the roadway. The high content of mineral powders significantly increases its brittleness. That's why sandy asphalts can only be used to a limited extent: landscaping parks or sidewalks. But coatings with a high content of bitumen are a welcome guest at any work: especially if it is road construction in harsh climatic conditions, with sub-zero temperatures, if the speed of work is such that after a day road equipment will go along the new road, and after the completion of the finished road, heavy vehicles will rush.